(1) Field of the Invention
The present invention relates to an optical disc read/write apparatus and alternative write processing method for performing an alternative write for a defective area on an optical disc when data is to be written onto the optical disc.
(2) Description of the Related Art
If a defective area is encountered in a data area when an attempt is made to write data onto a DVD or other optical disc, a method for performing an alternative write in the unit of a defective block by using an alternative area is employed to enhance there liability of the data to be written. If a request for performing a write in the unit of a sector is received although a write is performed on the disc in the unit of a block, a Read Modify Write process (herein after referred to as the RMW process) is performed. This process reads from the disc the data in a block that contains a requested sector, writes requested write data over the read data, and writes the resulting data in the unit of a block. The RMW process makes it possible to effectively perform a write and alternative write in the unit of a sector. The following technologies, which relate to improving an alternative process of an optical disc drive, are proposed.
A defect management method disclosed by Japanese Patent Japanese Patent Laid-Open No. 2005-293779 includes a process that divides an alternative block into a plurality of subblocks and sets identification information within defect management information for the purpose of differentiating replaced subblocks in which the data is replaced from unreplaced subblocks in which the data is not replaced when the alternative block (ECC block M) in an alternative area replaces an ECC block N containing a defective area on a DVD+RW disc.
A control function disclosed by Japanese Patent Japanese Patent Laid-Open No. 2000-339874 stores only the address of a defective block at the time of a continuous read and performs an alternative process after termination of the continuous read in order to prevent a real-time write operation from being interrupted by an alternative process during the use of a DVD-RAM disc.
The invention disclosed by Japanese Patent Japanese Patent Laid-Open No. 2006-85797 includes storage means for rearranging alternative sectors and writes rearranged data in an alternative area in order to avoid an increase in the seek time required for an alternative process in a situation where physically arranged alternative blocks in an alternative area are not written in the order of the addresses of defective blocks in a user area.